The development and fate of anti-DNA antibody producing cells and anti-IgG (Rheumatoid Factor) producing cells are being investigated in patients with SLE and RA respectively. Distribution of thymic derived and bone marrow derived lymphocytes and some of the factors influencing distribution are under investigation. In particular, spontaneously occurring antilymphocyte antibodies are examined for their effect on in vitro cellular function. Phlogistic potential of rheumatoid factors is being examined by studies on fixation of complement and in vitro studies on the influence of rheumatoid factors on non-complement dependent release of lysosomal enzymes from human polymorphonuclear leukocytes. Metabolism of immunoglobulins and complement in patients with RA and SLE is also under investigation. Central nervous system influence on experimental vasculitis is being studied in a model system in rats.